Growth and Characterization of Ge1-xSnx Layers for High Mobility Tensile-Strained Ge Channels of CMOS Devices

We have investigated the growth and characteristics of heteroepitaxial Ge1-xSnx layers on various substrates. The low temperature growth and the large misfit strain between Ge1-xSnx and Si leads to the high density of defects such as vacancy in Ge1-xSnx layers. They effectively enhance the propagation of misfit dislocations and the strain relaxation with suppressing the precipitation of Sn atoms from Ge1-xSnx layers. We succeeded in growing strain-relaxed Ge1-xSnx layers with a Sn content over 9% by controlling the dislocation structure on Si substrates. We also characterized the Hall mobility of Ge1-xSnx layers and found that the incorporation of Sn into Ge effectively reduced the concentration of holes related with vacancy defects, and improved on the hole mobility.